Re: [Regression] Laptop screen dark when lid closed and reopened.with 3.1

[Keith Packard]

On Tue, 25 Oct 2011 20:19:16 -0700 (PDT), Alex Davis <alex14641@xxxxxxxxx> wrote:

> At the request of Kamal Mostafa, an Ubuntu kernel developer, I am resubmitting this patch which fixes my backlight issue.
> It seem that there are a number of people with different machines that have this problem:

We have a patch that should land in a 3.1 stable release that should
resolve this issue; can you test that?

commit f52c619a590fa75276c07dfcaf380dee53e4ea4c
Author: Takashi Iwai <tiwai@xxxxxxx>
Date:   Fri Oct 14 11:45:40 2011 +0200

    drm/i915/panel: Always record the backlight level again (but cleverly)
    
    The commit 47356eb67285014527a5ab87543ba1fae3d1e10a introduced a
    mechanism to record the backlight level only at disabling time, but it
    also introduced a regression.  Since intel_lvds_enable() may be called
    without disabling (e.g. intel_lvds_commit() calls it unconditionally),
    the backlight gets back to the last recorded value.  For example, this
    happens when you dim the backlight, close the lid and open the lid,
    then the backlight suddenly goes to the brightest.
    
    This patch fixes the bug by recording the backlight level always
    when changed via intel_panel_set_backlight().  And,
    intel_panel_{enable|disable}_backlight() call the internal function not
    to update the recorded level wrongly.
    
    Cc: <stable@xxxxxxxxxx>
    Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
    Reviewed-by: Keith Packard <keithp@xxxxxxxxxx>
    Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>


-- 
keith.packard@xxxxxxxxx

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